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Fix closeHandle bug, add setFileSize, make resize work on Windows (#21375)

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* Add general purpose `setFileSize` (unexported for now).  Use to simplify
`memfiles.open` as well as make robust (via hard allocation, not merely
`ftruncate` address space allocation) on systems with `posix_fallocate`.

As part of this, fix a bad `closeHandle` return check bug on Windows and
add `MemFile.resize` for Windows now that setFileSize makes that easier.

* Adapt existing test to exercise newly portable `MemFile.resize`.

* Since Apple has never provided `posix_fallocate`, provide a fallback.
This is presently written in terms of `ftruncate`, but it can be
improved to use `F_PREALLOCATE` instead, as mentioned in a comment.
This commit is contained in:
c-blake 2023-02-15 11:41:28 -05:00 • committed by GitHub
commit c91ef1a09f
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3 changed files with 92 additions and 47 deletions
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11
lib/posix/posix.nim
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@ -195,8 +195,14 @@ proc open*(a1: cstring, a2: cint, mode: Mode | cint = 0.Mode): cint {.inline.} =
proc posix_fadvise*(a1: cint, a2, a3: Off, a4: cint): cint {.
importc, header: "<fcntl.h>".}
proc posix_fallocate*(a1: cint, a2, a3: Off): cint {.
importc, header: "<fcntl.h>".}
proc ftruncate*(a1: cint, a2: Off): cint {.importc, header: "<unistd.h>".}
when defined(osx): # 2001 POSIX evidently does not concern Apple
proc posix_fallocate*(a1: cint, a2, a3: Off): cint =
ftruncate(a1, a2 + a3) # Set size to off + len, max offset
else: # TODO: Use fcntl(fd, F_PREALLOCATE, ..) above
proc posix_fallocate*(a1: cint, a2, a3: Off): cint {.
importc, header: "<fcntl.h>".}
when not defined(haiku) and not defined(openbsd):
proc fmtmsg*(a1: int, a2: cstring, a3: cint,
@ -511,7 +517,6 @@ proc fpathconf*(a1, a2: cint): int {.importc, header: "<unistd.h>".}
proc fsync*(a1: cint): cint {.importc, header: "<unistd.h>".}
## synchronize a file's buffer cache to the storage device
proc ftruncate*(a1: cint, a2: Off): cint {.importc, header: "<unistd.h>".}
proc getcwd*(a1: cstring, a2: int): cstring {.importc, header: "<unistd.h>", sideEffect.}
proc getuid*(): Uid {.importc, header: "<unistd.h>", sideEffect.}
## returns the real user ID of the calling process